The present invention relates to folding furniture and, more specifically, to a counterbalancing assembly for an article of folding furniture.
Various forms of folding furniture are well-known in the prior art and are commonly used where available space within the area of use is limited. Such folding furniture is provided with a rotation system that allows for the rotation of a frame supporting cushion/mattress components (which may collectively be referred to as a “user-contacting portion”) or other furniture component (e.g., a table) between a storage position and a use position. Typically, the storage position is substantially upright (or vertical), and the user-contacting portion or other furniture component is housed in a decorative cabinet in this storage position. The use position is substantially horizontal, allowing the user to sit or lie on the cushion/mattress components held by the supporting frame, or allowing the user to otherwise use the furniture component. Because the combined weight of the elements that make up the user-contacting portion or other furniture component can be considerable, counterbalancing mechanisms are frequently employed that allow an individual to easily raise the user-contacting portion or other furniture component to the substantially upright storage position.
Various counterbalancing mechanisms have been developed for such folding furniture, including spring systems, counterbalancing hinges, and piston-based arrangements. Piston-based arrangements have proven to be especially effective in heavier applications, such as the counterbalancing of the weight of a wall bed, which includes the weight of the frame and the mattress (and possibly box springs). Examples of such piston-based arrangements are described in U.S. Pat. Nos. 5,033,134; 5,978,988; and 8,006,327, each of which is assigned to the assignee of the present application and is incorporated herein by reference. As described in U.S. Pat. Nos. 5,033,134; 5,978,988; and 8,006,327, two gas-filled counterbalance pistons, which provide an appropriate resistive force to the gravitational force acting on the frame and mattress, are secured to the inside surfaces of a wall-mounted cabinet (housing the frame and mattress in the substantially upright storage position) and to the sides of the frame. The pistons are biased to resist, i.e., counterbalance, the downward force of gravity acting on the frame and mattress, thus assisting in both the lowering of the frame and mattress to the use position and the lifting/returning of the frame and mattress to the substantially upright storage position.
U.S. Pat. No. 5,978,988 also describes the problem of variances in the weight of the user-contacting portion or other furniture component. To properly counterbalance the weight of the user-contacting portion or other furniture component, the pistons must be carefully selected, and the mounting locations for the piston ends must also be carefully selected. Variances in the weight complicate the selection of the pistons and the mounting locations. For example, with respect to a wall bed, the substitution of a particle board material for lighter board material for the frame is likely to require the use of heavier pistons with greater resistive counterbalancing force and/or change in the mounting locations. Such changes of the pistons and/or mounting locations can be both time-consuming and expensive, and may prove impractical to the end user who innocently changes the component weight.
U.S. Pat. No. 5,978,988 describes one solution to the problem of variances in the weight. Specifically, U.S. Pat. No. 5,978,988 describes a folding furniture apparatus with a counterbalancing system that creates one of a selected value of torques about a pivot axis to bias the user-contacting portion or other furniture component to the substantially upright storage position. The folding furniture apparatus thus includes at least one upper mounting bracket mounted to a support assembly (such as a wall-mounted cabinet) and a lower bracket mounted to the user-contacting portion or other furniture component, each of these brackets having a plurality of corresponding mounting points. The counterbalancing piston is pivotally secured to and extends from a selected mounting point on the lower bracket to an associated mounting point on the upper bracket. The lower mounting points and associated upper mounting points are preselected to provide the necessary counterbalancing (torque) for a certain weight of the user-contacting portion or other furniture component without requiring the use of a different piston or relocation of the mounting hardware. In other words, a user can move the piston and mount it to a different pair of mounting points to vary the counterbalancing torque that is applied to the user-contacting portion or other furniture component. However, this does require the disconnecting and reconnecting of each piston to the respective mounting brackets.